DIY tool post grinder plans or advice needed.

[GoceKU]

I've been needing an tool post grinder for a some time now but never could find one to buy and my previous attempt with using a 1,5 hp 2800 rpm motor and a cap wheel direct drive did not work well at all, i need some advice, what RPM to aim for and what power size motor to use for stones i have a selection from 20 to 100mm in diameter.

 

[Bob Korves]

When doing grinding with varying size wheels, you have to think of speed in surface feet per minute (SFPM) or in meters per second (MPS) or you will never get things right. Here is a calculator if that helps:
http://www.abrasiveengineering.com/spedcal2.htm
Speed chart: http://www.abrasiveengineering.com/speeds.htm
Various materials do not seem to make much difference for what speeds to use.

 

[Bob Korves]

Speed equals wheel diameter times Pi times rotational speed. Make sure the units match.

 

[Ulma Doctor]

some TP grinders have 20,000 rpm spindle speeds.
the bearing quality will directly affect the surface finish, as will wheel selection.
direction of motor rotation can also be critical for good surface finish

 

[Bob Korves]

I have a Dumore 44-011 tool post grinder as an example. Dumore makes larger and smaller grinders. It is reasonably small, but works great on my 13" (~325mm) swing lathe.
https://www.dumoretools.com/tool-post-grinders
Here is the manual:
https://www.dumoretools.com/documents/Tool-Post-Grinders-Dumore-Series-44-Operating-Instructions.pdf
The parts list starts on page 12. It comes with five different sized pulleys to achieve speeds from 6600 to 38,500 rpm.
Grinders of this type do not remove large quantities of material quickly. You are not going to hog 1/8" (3mm) out of the interior of a 1" (25mm) bore without spending a lot of time at it. The bearings are high precision, the mounting and structure is suitably rigid, and the grinder is capable of accurate work with nice shiny surface finish -- if you know how. I got it with a lot of tools and paid around $200-300 U.S. for it, in essentially new condition, maybe used once or twice, and came with many extra wheels and extra tooling besides all the factory stuff, in the factory case. It has no problems whatsoever. If you check the prices of these grinders new, your jaw will drop. Replacement parts are equally high priced, I have not needed any, and will try to make sure I never need any beyond industry standard consumables. It comes with grinding wheels from 1/4" (6mm) to 3" (75mm) diameter. Getting good results with the smallest wheels is just as important as with the largest wheels. More questions, please ask.

 

[Ray C]

Try this: http://hobby-machinist.com/threads/tool-post-grinder-making-a-new-one.19687/

Regards

Ray C.

 

[Suzuki4evr]

I've been needing an tool post grinder for a some time now but never could find one to buy and my previous attempt with using a 1,5 hp 2800 rpm motor and a cap wheel direct drive did not work well at all, i need some advice, what RPM to aim for and what power size motor to use for stones i have a selection from 20 to 100mm in diameter.

Just a thought......check out my thread on Tool post grinder. That is what I did with that size motor.

 

[GoceKU]

Thank you all for the suggestions, i've got a pretty good idea now how the factory one's work and what i need my to do, so i've started buying parts and have a plan, i'll open a build thread when i start the build.

 

[Suzuki4evr]

Can't wait too see your posts.

 

[GoceKU]

I've started an build thread for my tool post grinder, i'm still in the beginning stages, here is an link : https://www.hobby-machinist.com/threads/tool-post-grinder-build.65357/